Cylinder etching machine



0d. 1944- c. L. HENDERSON ETAL ,5

CYLINDER ETCHING MACHINE Filed July 28', 1941 5 Sheeis-Sheet 1 r INVENTOCharles L. fi'rzdefs n Che/view .2? Powers 1944- c. HENDERSON ET AL2,360,575 CYL INDER ETCHING MACHINE Filed July 28, 1941 5 Sheets-Sheet 2Fig.2. 09 C INVENTORS: Charles .5. Henderson BY Chesz'er" 16. Powers 00L1944- c. L. HENDERSON ETAL CYLINDER ETCHING MACHINE Filed July 28, 1941&

5 Sheets-Sheet '3 o Q m Q INVENTORS! Charles L Henderson BY 6706575297"1?. Pours/"'6 a1: an L jd d Oct. 17, 1944.

C. L. HENDERSON E'I'AL CYLINDER ETCX-IING monum- 5 Sheets-Sheet 4 IFiled July 28, 1941 III,

[III/III,

INVENTORS C/wowlies L. Heads Yv W l N w Oct. 17, 1944. L HENDERSON ETAL,360,676

CYLINDER ETCHING MACHINE Filed July 28, 1941 5 Sheets-Sheet s I I W6)" II INVENTORS:

Charles L. Hendersom BY t Paws 15 flan/no, 4 I

v Wigs Patented Oct. 17, 1944 V mm ETCHING momma Charles L. Hendersonand Chester Powers, Appleton, Wis., assignors .to Paper Patents Company,a corporation of Wisconsin Application July 28, 1941, Serial No. 404,33812 (oral-9) The present invention relates particularly to apparatus andmethods for etching intaglio or relief printing cylinders.

In intaglio printing the printing surface comprises a smooth, metallicsurface, usuallyof copper, havin formed therein, by etching orotherwise, symmetricall'y arranged ink-receiving recesses of very smallarea. The ink recesses throughout the printing surface areseparatedbyline-like, unetched lands, which serve to support the doctor or scraperblade used for removing excess ink from the printing surface during theactual printing operation.

During the manufacture of intaglio printing cylinders, it is customaryto employ a light sensitive film or resist, which asmanufactured issoluble in water or other solvent but which becomes insoluble whenexposed to light, and to transfer the image or design to be reproducedto the resist photographically. The resishmay be formed upon the surfaceof the metallic plate orcylinder by application thereto in liquid form,or it may be in the form of a sheet, such as carbon tissue, which iswrapped around the printing cylinder or otherwise applied to the surfaceafter the transfer operation, as in the rotogravure process. The imageor design which is to be reproduced in the printing surface is broken upinto small opaque dots, either before or during the transfer operation.The line-like areas between the opaque dots are exposed to light duringthe transfer operation, and the resist in those areas is renderedinsoluble.

Following the transfer operation, the resist is washed, to eitherpartially or wholly remove the unexposed dot areas, and is hardened. Thesurface is then etched by iunnersion in a suitable etching fluid orother procedure. During the etching the light insolubilized, line-likeareas of resist intermediate the dot areas protect the lmderlyingportions of the; printing surface from 1 the etching fluid, and as aresult the etching takes place only in the unexposed dot areas whichished printing plate.

The manufacture of relief cylinders may follow a similar process. as isknownin the art.

'lnthepas'hdifficultyhasbeenexperiencedin effecting completelysatisfactory etching of cylin- 35 .6 is a fragmentary perspective viewillus-j areas which are different in tone from the main body of theetching, the efiect being known as shading. p Y

The principal object of the present invention is to overcome thisdifiiculty which is inherent in the prior art etching procedures, and toprovide amachine and method whereby uniformly etched surfaces, free fromshading, can be produced by a. relatively simple etching operation. Itis also an object of our invention to provide an improved etchingmachine, particularly adapted for etching printing cylinders, which canbe operated to produce a very uniform etch of excellent printingcharacteristic. Other objects and the various advantages of theinvention will be made apparent by reference to the accompanyingdrawings and the following description of one preferred embodimentthereof. In the drawings:

Fig. 1 is an and elevation of an etching machine constructed inaccordance with the present invention; I a

Fig. 2 is'a-sectional view of the machine illustrated in Fig. l, theview being taken on the line 2'2 of that figure;

Fig. 5 is a fragmentary sectional view-showingthe details of one of theresilient bearing supports for the sealing rolls forming a part of themachine illustrated in the other figures of the trating one means ofadapting the apparatus of the other figures'of the drawings for use inconnection with short rolls;

Fig. 'l is a sectional view, generally similar to 40 Fig. 4, of amodified form of the apparatus of Fig. 7. thereby become ink-receivingrecesses in the fin the present invention; and

Fig. 8"is a sectional view on the line 8-8 of Referring particularly toFigs. 1 and 2, the apparatus therein illustrated includes a rectgns'u-.larly-shaped outer tank ll of relatively haw,

reinforced, wood construction whichis supported upon four uprights l3and a rigid, metallic frame l5,

wallsmaybesplashedwith acidor other etching fluid, the wood of which thetank Ills constructed should be impregnated or painted withanacid-resistlng compound.

The etching fluid is contained within a. boxlike container or tank l1,preferably made of wood'whichhas been coated or otherwisetreatedtorender it acid-resistin Thetank I1 issuppcrtedadjacent-theopentopofthemaintank-Theoutertankllisopenatthetopandserves to contain the other elements ofthe ap Because of the possibility that the tank II by means of suitablehollow support members N) (Fig. 3), having bracket portions 2| afflxedto the two ends of the main tank II by suitable lag screws 23, asillustrated. The acid or other etching fluid is applied to the surfacewhich is to be etched by means of a rotatable impeller member 25 and animpeller housing 21 which cooperates therewith. The impeller housing 21comprises an elongated, open-mouthed, rigid vesvel'having the generaloutline illustrated in Figs. 4 and 6. It is bolted to one of the supportmembers l9 at each of its ends, and thereby supported in proper positionwithin the tank l! for the etching fluid. The impeller housing 21comprises two complementary half sections of cast iron which are boltedtogether by suitable bolts 28. The housing 21 is coated withacid-resisting material and is open along its lower edge, as illustratedat 29, to permit free entry of the etching fluid thereinto. a

The impeller 25 of the apparatus illustrated in the drawings comprises aseries of paddle members 3| made of an acid-resisting plastic, such asthat sold under the trade name of Lucite, or of some otheracid-resisting material, which are affixed to a suitable rotatable shaft33., One end of the shaft 33 extends through an opening 35 in the maintank I I, as illustrated in Fig. 3, for connection to amotor 31 (Fig. 2)or other rotating means.

I The impeller 25 is supported for free rotation within the impellerhousing 21 by suitable bear-' ings 39 (Fig. 3), which in turn aresupported in the hollow support members l9. To prevent acid carry-overinto the bearings 39 during the operation of the apparatus, a labyrinthseal 4| is provided at each end of the impeller housing 21, and this isbacked up at each end of the machine by a gland seal 43. The motor 31which is used for rotating the impeller 25 is supported upon a bracket45 aflixed to the adjacent end of the main tank H and is connected tothe impeller shaft 33 by a belt 41 and suitable pulleys l9 and Avariable speed motor is preferred.

In order to confine the etching fluid which is discharged through themouth 53 of the impeller housing 21 by operation of the impeller 25, themachine is provided with two longitudinally-extending sealing rolls 54and 55 which are supported for free rotatable movement by means ofcentral shafts 55 and spaced bearings 51 which form a part of thesupport members l9. The sealing rolls 54 and 55 are identical inconstruction and should be made of fairly soft, acid-resisting rubber orrubber compound. Rolls of sufficient -softness to give aplastometer-reading of about 140 with a /4 inchball have provenparticularly satisfactory. To prevent acid from being carried into thesupporting bearings '51 for the sealing rolls, the bearing supportingstruc ture includes a liquid deflector 59 anda gland seal 8 l as shownin Fig. 3.

Printing cylinders vary considerably in length and in diameter, and asatisfactory etching machine should include means for accommodatingcylinders of varying dimensions. In the particular machine illustratedin the drawin s, this means includes an adjustable bearing supportstructure for the cylinder which is to be etched.

This structure includes a hydraulic operating mechanism 63 (Figs. 1 and2) having a movable which is mechanically connected to' a piston 65longitudinally-extending beam 51, a pair of vertically movable supports,one of which is located at either end of the apparatus, and means {or 15mechanically interconnecting the supports so as to assure uniformmovement thereof in response to movement of the hydraulic piston 65 andthe beam 61. Each of thev'ertlcally movable supports includes a yoke 63,which is rigidly afiixed to an upper crosshead ll. Theupper crosshead 1|is bolted to two spaced, cylindrical guides 13 which are supported forslidable vertical movement in suitable spaced guideways 15 and I1rigidly affixed to either end of the main tank II. To limit the downwardmovement of the vertically movable supports, and for other reasons, asecond crosshead member 19 is keyed to the two cylindrical-guide members13, as illustrated in Figs. 1 and 2. The lower crosshead member 19 atthe right hand end of the apparatus (Fig. 2) has afllxed thereto aplatform 8] which serves as the support for a motor 83. This motor 83may be connected to ,the shaft 85 of the cylinder being etched by asuitable belt. 81 and pulleys89 and 9| for the purpose or rotating the,cylinder during the etching operation. To permit free rotation of theprinting cylinder during the etching operation, suitable ball bearings93 are placed over the ends of the shaft 85 of the cylinder. Thesebearings 93 rest on the yokes 59, as illustrated, 1

Each of the lower crossheads 19 i adjustably connected to one end of thelongitudinallyextending beam 61 by means of a'rod member 95, having athreaded portion 91 at its lower end, and a pair of adjusting nuts 99.To assure equal uniform movement of the two vertically adjustablesupports for the printing cylinder, each of the rod members 95 extendingbetween the lower crossheads I3 and the beam 61 is provided with twodiametrically spaced rack sections HM, and the pair of rack sections oneach side of the machine are interconnected by a transverselyextendingshaft I03 and suitable pinion gears I05 keyed thereto. The shafts I03are rotatably supported on the main frame l5 of the machine by rigidbearings llll (Fig. 2).

Fig. 5, include a rigid guideway 3, a cylindrical bearing support member5 located in said guideway and movable in a vertical direction relativethereto, aspring II! which normally biases the bearing support member H5(and the bearing) in an upward direction, and a tension adjusting meansI IQ for the spring I 11. During the operation of the apparatus, thevertically adjustable supports for the cylinder to be etched will belowered by the operation of the hydraulic operating mechanism 83 untilthe cylinder resiliently engages and seals with the sealing rolls. Thesealing pressure can be readily controlled by adjusting the tension ofthe spring H1.

During the actual etching operation it is de sirable that the printingcylinder which is to be etched should be rotated at a relatively slowspeed, and tests indicate that cylinder speeds within the range of fromabout 10 to 12 R. P. M. are particularly satisfactory for etching coppersurfaces with perchloride of iron. The impeller I leakage or dischargeof the etchin fluid from the.

space between those rolls and the encompassed portion of the cylinderwhichis being etched. At

the same time, the sealing roll 55 acts to doctor off excess etchingfluid from the cylinder as it rotates, and prevents any substantialquantity of that fluid from remaining on the cylinder after it passesthe sealing roll. To prevent any carryover of etching fluid on the othersealing r'oll'54, the apparatus includes a longitudinally-extendingrubber doctor I2I which is supported upon the adjacent edges of the tankH for the etching fluid, as illustrated particularly in. Fig. 4. The

v doctor I2I continuously returns any of the etchin fluid which mayaccumulate on the sealing roll 54 to the main body of the etching fluidcontained in the tank II. A longitudinally extending sealing doctor I23,also supported on the tank". engages the lower surface of the sealingroll 55 to prevent discharge of the etching fluid along that edge of thetank.

When the etching operation has been completed it is usually desirable towash oil the etching fluid as quickly as possible. To facilitate thisoperation the apparatus includes a pivotally supported metallic apron ordeflector I25 which is of such design that it may be swung into placefrom the inoperative iposition illustrated in full in Fig. 4 to theoperative position illustrated by the dotted lines of that figure. Inits operative position the apron I25 covers the sealing rolls 54 and 55and the space therebetween which would otherwise open into the etchingfluid tank I'I. Before moving the apron I25 into place, it is of coursenecessary to raise the cylinder to a position a'bove that occupied bythe protective apron. and th s is accomplished by operation of thehydraulic elevatingmechanism 63 for the cylinder supports. The elevatedposition of small and large cylinders are illustrated by the dottedoutlines of Fig. 4. Following the elevation of the. cylinder and themovement of the apron to operativeposition, the cylinder can be washedimmediately by a hose or other means without'risk of diluting orcontaminating the etching fluid. The washing liquid will be collected inthe main tank from which it can be conveniently discharged.

When etching relatively short cylinders, it will atomizing structureI21, as illustrated, includes a pair of complementary, machined platemembers I29 which are designed so as to provide a plurality of regularlyspaced atomizing jet cham bers I3I which open into wedge-shaped throatsI33 wherein are disposed deflector members I35 for dividing anddirecting the atomized stream so as to assure full coverage at the openupper end of the throat. The complementary plate members I29 are boltedtogether and are held 'in place within a suitable tank I'I'-A for theadjustable support means for the cylinder which is to be etched areexactly the same in this apparatus as in the previously describedstructure.

Doctors I2 I-A and I23-A similar to the doctors HI and I23 are providedfor preventing excess etching material from being carried around onthe,sealing rolls 54 and 55.

Tests have shown that-the etching apparatus which has been described inthe foregoing is capable of producing gravure cylinders which aresubstantially completely free from shading or other defects. Apparentlybecause the etching fluid is continuously applied to a portion of therotating cylinder and is continuously doctored off at the edges of suchportion, the etching operation takes place very uniformly and is capableof easy and convenient control. This accomplishes the highly desirablefunction of making it possible to carry out the etching of printingcylinders conveniently and. efficiently.

It will be apparent that the apparatus and methods described in theforegoing can be used be found desirable to partially cover both ends ofthe impeller housing with an acid-resisting, removable cover I 21, asillustrated in Fig. 6. c This arrangement confines the discharge oftheetching fluid to the length of the cylinder which is'to be etched. j

The modified form of the apparatus illustrated in Figs. 7 and 8 isessentially similar to'the machine which has been described in theforegoing, with this one important exception: In-the modifled apparatus,the etching fluid is directed against the surface to be, etched by meansof a liquid jet atomizing structure I21 which is operated by a pluralityof spaced air jets. The

by the prior .art and the express language thereof.

We claim: 1. In combination in apparatus of the class described, acylinder, a pair of spaced horizontally-extending sealing rolls whichcontact said cylinder, and spray means operable/ to provide a spray ofetching fluid which is directed onto thatportion of the surface'of saidcylinder which is between said sealing rolls. I

2. In combination in apparatus of the class described, a cylinder, apair of spaced, generally parallel, horizontally-extendingsealingmembers which resiliently contact said cylinder ing the operationof said apparatus, spray me s operable to provide a spray of etchingfluid which is directed onto that vportion of the surface of saidcylinder which is between said sealing members, and means for movingsaid surface through said spray during the etching operation. 3. Incombination in apparatus of the class described, a cylinder, means forsupporting said cylinder for rotation about its longitudinal axis, meansfor rotating said'cylinder during the opoperable to provide anelongated, relatively narrow spray of etching fluid which is directedonto the surface of said cylinder along the length thereof, and meansincluding a pair of spaced, generally parallel, longitudinally-extendingrolls which contact the surface of said cylinder at either side of saidspray for restricting the area of said cylinder which is contacted bysaid spray and for continuously doctoring off the etching fluid from thecylinder surface as it passes out of said spray.

5. In combination in apparatus of the class described, a printingcylinder, an elongated, boxlike tank which has an open top and whichcontains a quantity of etching fluid, means for mentioned meansincluding an elongated, boxlike tank which contains a quantity ofetching spaced, generally parallel, horizontally-extending supportingsaid cylinder for rotation adjacent the open top of said etching fluidtank, means for rotating said cylinder, means located within saidetching fluid tank which is operable to provide an elongated, relativelynarrow spray of etching fluid and to direct said spray onto the adjacentsurface of said cylinder along the length thereof, and means forcontinuously doctoring ofl. the etching fluid from the cylinder surfaceas it passes out of said spray.

6. In combination in apparatus of the class described, a printingsurface, horizontally-extending support means for said surface, andmeans operable to provide a spray of etching fluid which is directedonto said surface to eflect the etching thereof, said last-mentionedmeans.

including an elongated, box-like tank which contains a quantity ofetching-fluid, an elongated impeller housing located within said tank,and a rotating impeller located within said impeller housing, saidimpeller housing having an elongated, relatively narrow throat throughwhich the etching fluid is directed onto said cylinder.

'7. In combination in apparatus of the class described, a printingcylinder, means for supporting said cylinder for rotation about itslongitudinal axis, means for rotating said cylinder, and means operableto. provide an elongated, relatively narrow, spray of etching fluidwhich is directed onto the surface of said cylinder along the lengththereof, said last-mentioned means including a rotating impeller, andanelongated impeller housing within which said impeller rotates, saidimpeller housing having an elongated, relativelynarrow throat throughwhich the etching fluid is directed onto said cylinder.

8. In combination in apparatus of the class described, a printingsurface, a pair of spaced, generally parallel, horizontally-extendingsealing rolls upon which said surface rests during the operation Ofsaidv apparatus, and means operable to provide a spray of etching fluidwhich is directed onto that portion of said surface which is betweensaid sealing rolls, said lastsealing rolls, each having a resilientouter surface upon which said cylinder rests during the operation ofsaid apparatus, means for rotating said cylinder and thereby alsorotating said sealing rolls, and spraymeans operable to provide a sprayof etching'fluid which is directed onto that portion of said cylinderwhich is between aid sealing rolls, said sealing rolls continuouslyoctoring off the etching fluid from the cylinder surface as it passesout of s id spray.

10. In combination in a paratus of the class described, a printingcylinder, vertically adjustable means for supporting said cylinder forro-- tation about its longitudinal axis, a pair of spaced, generallyparallel, horizontally-extending sealingrolls, each having a resilientouter surface upon which said cylinder rests during the operation ofsaid apparatus, means for rotating said cylinder and thereby alsorotating said sealing rolls, and means operable to provide an elongated,relatively narrow, spray of etching fluid which is directed onto thatportion of said cylinder which is between said sealing rolls, said sprayproviding means including an, elongated, box like tank which contains aquantity ,impeller housing having an elongated, relatively narrow throatthrough which the etching fluid is directed onto said cylinder.

11. In combination in apparatus of the class described, a printingcylinder, a pair of spaced, generally parallel, horizontally-extendingsealing rolls upon which said cylinder rests during the operation ofsaid apparatus, means for rotating said cylinder, and means operable toprovide an elongated, relatively narrow spray of etching 'fluid which isdirected onto the surface of said cylinder along the length thereof,said last-mentioned means including a plurality of spaced jet typeatomizing nozzle mechanisms and a source of pressure air.

12. In combination in apparatus of the class described, means forsupporting a cylinder to be etched for rotation about its longitudinalaxis, means for rotating said cylinder during the etching operation,spaced, horizontally-extending sealing members which are adapted toengage the surface of said cylinder along elements thereof to provide arestricted longitudinal pe-. ripheral area on said cylinder exposed tothe acid spray, and. spray means operable to provide .a spray of etchingfluid which is directed 1 onto the surface of said cylinder between saidsealing members.

CHARLES L. HENDERSON. CHES'I'ER R. POWERS.

